Lateral sphincterotomy (Lateral internal sphincterotomy)

A short operation to heal a long-standing anal fissure by making a small, deliberate cut in part of the tight inner muscle of the anus to release its spasm and improve the tear's blood supply.

✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review

In short

It is a short, usually day-case operation that heals the large majority of chronic anal fissures.
Because it permanently divides part of the anal muscle, it carries a small risk of reduced control of wind or stool — this is the central trade-off.
It is usually reserved for a chronic fissure that has not healed with creams, fibre and fluids, not as a first step.
It is generally avoided, or used very cautiously, in people who already have weak control or are at higher risk — a botulinum toxin injection or advancement flap may be safer for them.

A plain-English summary. The detail — including risks and recovery — is below.

At a glance

TypeSurgical procedure for a chronic anal fissure

AnaestheticUsually a general anaesthetic; sometimes a spinal or local anaesthetic

How long it takesUsually around 10–20 minutes

Hospital stayUsually a day case — home the same day

Time off workOften a few days to about a week, depending on your job

When you'll see resultsPain often eases within days; the fissure usually heals over a few weeks

On the NHS?Commonly available on the NHS for a chronic fissure that has not healed; also offered privately

A general guide. Your surgeon will give you advice for your situation.

Best fit

Heals the large majority of chronic anal fissures

Pause if

People who already have impaired control of stool or wind, in whom dividing muscle adds risk.

Main recovery point

Expect some soreness, a little bleeding and possibly discharge. Use pain relief, take stool softeners as advised, and have warm shallow baths for comfort.

Good aftercare

A written plan for keeping stools soft with fibre, fluids and laxatives.

First few days

Expect some soreness, a little bleeding and possibly discharge. Use pain relief, take stool softeners as advised...

First week

Many people return to desk-based work within a few days to a week. The sharp pain on passing stool usually starts...

2–6 weeks

The fissure heals in most people. Any early difficulty controlling wind usually improves over this time.

From 6 weeks

Most fissures are healed and pain has settled. Tell your surgeon if pain continues, the fissure returns, or you...

Medical line illustration of lower rectum and anal canal treatment anatomy for Lateral sphincterotomy. — Illustration only - not a diagnosis, medical advice or a promise of result. Your anatomy and treatment plan may differ. Vuemedics does not publish before-and-after photos.

What is a lateral sphincterotomy?

A lateral internal sphincterotomy is an operation to treat a chronic anal fissure — a tear in the lining of the anus (back passage) that has not healed despite creams, fibre and fluids. It is one of several options for a fissure that will not settle, and is often described as the most effective surgical treatment.

In a chronic fissure, the inner ring of muscle around the anus (the internal sphincter) is often in spasm. This squeezes the area, reduces its blood supply and stops the tear healing. In a sphincterotomy, the surgeon makes a small, deliberate cut in part of this muscle to release the spasm and let the fissure heal.

The cut is placed to the side ('lateral'), away from the fissure itself, and only part of the muscle is divided. It is usually done through a tiny opening that is left to heal on its own.

The main thing to understand is the trade-off. The operation heals the large majority of chronic fissures, but because it permanently divides a small part of the muscle, it carries a small risk of reduced control of wind or stool. This is why it is not used for everyone, and why other options exist.

Types & techniques

There isn't one single operation. The right approach depends on you — which is something to discuss with your surgeon.

Open lateral internal sphincterotomy

The surgeon makes a small cut in the lining to see the muscle directly before dividing part of it. The small wound is usually left to heal naturally.

Closed lateral internal sphincterotomy

A fine blade is passed through a tiny opening to divide part of the muscle without a larger cut in the lining. Studies suggest open and closed techniques give broadly similar results.

Tailored sphincterotomy

The amount of muscle divided is limited (for example to the top of the fissure rather than higher), aiming to reduce the risk to continence while still allowing healing.

Combined with fissurectomy

The chronic edges of the fissure may be trimmed at the same time to encourage fresh healing.

Sphincterotomy vs botulinum toxin injection

Point	Sphincterotomy	Botox injection
Effect on muscle	Permanent small cut	Temporary relaxation
Healing	Heals the large majority	Works for many, less reliable
Risk to control	Small but real	Very low
Recurrence	Less likely	More likely
When chosen	Firm result, injection failed	Avoid cutting, higher continence risk

Sphincterotomy is generally the more reliable for healing, but a botulinum toxin injection avoids any lasting effect on the muscle. The right choice is individual.

Preparing for your surgery

See the operating surgeon, who should examine you and confirm the fissure is chronic and in the usual position.
Make sure creams (GTN or diltiazem), fibre and fluids have been given a fair trial, as this operation is not usually a first step.
Be honest about any existing problems controlling wind or stool — this is the most important thing in deciding whether this operation is right for you.
Tell your surgeon about childbirth-related tears, previous anal surgery, or inflammatory bowel disease.
List all medicines, including blood thinners, and follow fasting advice for your anaesthetic.
Arrange laxatives or extra fibre for afterwards so stools stay soft.
Arrange a lift home, and someone with you for 24 hours if you have a general anaesthetic.

What happens

The operation is usually done as a day case under a general anaesthetic, though a spinal or local anaesthetic is sometimes used. You will not feel the procedure.

The surgeon examines the anus and confirms the fissure. A small, deliberate cut is then made in part of the internal sphincter muscle, to the side and away from the fissure, to release the spasm. This is often done through a tiny opening that is left to heal naturally. The chronic edges of the fissure may be trimmed at the same time.

The operation usually takes only about 10 to 20 minutes. Afterwards you recover in the unit and most people go home the same day with advice on pain relief and on keeping stools soft while the fissure heals.

Is this operation right for me?

A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.

May not be suitable if…

People who already have impaired control of stool or wind, in whom dividing muscle adds risk.
Many women with previous obstetric (childbirth) injury to the anal muscles, where continence risk is higher.
Fissures in an unusual position or multiple fissures, which need investigation for another cause such as Crohn's disease first.
An acute fissure, or one that has not had a fair trial of fibre, fluids, softer stools and creams.
Low resting muscle pressure, where releasing more muscle is not appropriate.

Delay surgery if…

There is an active infection, abscess or undiagnosed swelling near the anus.
Conservative measures and creams have not yet been properly tried.
Inflammatory bowel disease is suspected but not yet assessed.
There are unexplained changes in bowel habit, weight loss or bleeding needing investigation.
Existing bowel control has not been assessed in someone at higher risk.

Alternatives to discuss

Continued conservative care with fibre, fluids, softer stools and warm baths.
Topical creams such as GTN or diltiazem.
A botulinum toxin injection, which avoids cutting muscle.
An anal advancement flap, which can protect continence.
Treating an underlying cause such as inflammatory bowel disease.

Before you decide

Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.

What matters most to me?

Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.

What are all my options?

Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.

What would make me pause?

Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.

What happens if I do nothing today?

For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.

Anaesthetic choices

The safest option depends on the operation, your health, the facility and your surgeon/anaesthetist. Ask what is planned and why.

General anaesthetic

Commonly used; you are fully asleep for the short operation.

Spinal anaesthetic

Numbs the lower body; sometimes used as an alternative to a general anaesthetic.

Local anaesthetic

Used in selected people for this brief procedure.

Benefits

Heals the large majority of chronic anal fissures
Often gives quick relief from the sharp fissure pain
Lower chance of the fissure returning than after a botulinum toxin injection
A short, usually day-case operation with a quick recovery for most people
Stopping the pain makes it easier to keep stools soft and avoid a relapse

Risks & complications

More common

Soreness, a little bleeding or discharge for a few days afterwards
Temporary, minor trouble controlling wind in the early weeks
Needing stool softeners or laxatives for a while
Slow healing of the small wound in some people

Less common

Infection or a small abscess at the site
Bleeding that needs medical attention
Longer-lasting difficulty controlling wind or loose stool
The fissure not fully healing or coming back

Rare but serious

Lasting incontinence of solid stool — uncommon but the most important risk to understand and weigh up
A small tunnel forming between the anus and the skin (fistula)
A keyhole-shaped deformity of the anus that can cause minor leakage
Risks related to anaesthetic

The defining risk of this operation is its effect on bowel control. Minor, temporary trouble controlling wind is common in the early weeks. Across studies, some disturbance of continence is reported in a minority of people, and lasting incontinence of solid stool is uncommon. The risk is higher in women, in older people, and in anyone with weak control or a past childbirth injury — these groups should specifically discuss whether a botulinum toxin injection or advancement flap is safer for them.

Published figures to discuss

Reported outcomes vary with technique (open or closed), how much muscle is divided, how 'incontinence' is defined, and how long people are followed. Minor, temporary trouble with wind is common; lasting incontinence of solid stool is uncommon. Healing and recurrence figures come from research series and meta-analyses and indicate magnitude rather than your exact personal risk.

Figure	Reported range	How to interpret it	Source / confidence
Fissure healing	Around 90% or more in pooled studies	Often described as the most effective surgical treatment for chronic fissure.	StatPearls (NCBI) — Internal Anal Sphincterotomyncbi.nlm.nih.govPublished figure
Fissure recurrence	Low single figures (around 3–4% in some meta-analyses)	More likely if constipation and straining continue.	StatPearls (NCBI) — Internal Anal Sphincterotomyncbi.nlm.nih.govPublished figure
Any disturbance of continence	Reported around 8–14% across studies (mostly minor, such as wind)	Definitions vary widely; much of this is temporary.	StatPearls (NCBI) — Internal Anal Sphincterotomyncbi.nlm.nih.govPublished figure
Major incontinence (involuntary loss of solid stool)	Uncommon — reported under about 2% in long-term pooled data	Higher in women, older people and those with prior weakness or obstetric injury.	StatPearls (NCBI) — Internal Anal Sphincterotomyncbi.nlm.nih.govPublished figure

These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.

Recovery — what to expect, and when

Recovery is usually quick. Many people notice the constant fissure pain easing within days, and the tear typically heals over a few weeks, as long as stools are kept soft.

First few days

Expect some soreness, a little bleeding and possibly discharge. Use pain relief, take stool softeners as advised, and have warm shallow baths for comfort.

First week

Many people return to desk-based work within a few days to a week. The sharp pain on passing stool usually starts to settle. Avoid straining.

2–6 weeks

The fissure heals in most people. Any early difficulty controlling wind usually improves over this time.

From 6 weeks

Most fissures are healed and pain has settled. Tell your surgeon if pain continues, the fissure returns, or you still have trouble with control.

What's normal — and not a worry

Soreness and a little bright bleeding when you poo in the first days
Some clear or blood-stained discharge while the small wound heals
Mild, temporary trouble holding wind in the early weeks
The sharp fissure pain easing within days to a couple of weeks

Aftercare

Take stool softeners, laxatives or extra fibre as advised so you do not strain.
Drink plenty of fluids and eat a higher-fibre diet.
Have warm, shallow baths, particularly after a bowel movement, to ease discomfort and keep the area clean.
Use any prescribed pain relief or cream as directed.
Keep the area clean and dry, patting rather than rubbing.
Avoid heavy lifting and strenuous activity in the first week or so if advised.
Contact the clinic if you have worsening pain, fever, heavy bleeding, or new trouble controlling stool.
Attend any follow-up so healing and continence can be checked.

Before-surgery checklist

Stool softeners or laxatives obtained as advised
Higher-fibre foods and plenty of fluids planned
Pain relief and any prescribed cream ready
Time off work arranged (a few days to about a week)
Lift home arranged if you have a general anaesthetic
Clinic's contact number saved for problems

Scars and how they heal

A lateral sphincterotomy usually leaves little or no visible scar. The cut in the muscle is internal, and the small opening used is often left to heal naturally, leaving only a tiny mark. Some soreness or slight firmness at the site can be normal while it heals.

⚠ Get urgent help if…

Heavy or persistent bleeding from the back passage
Severe or worsening pain not controlled by your pain relief
A high temperature or feeling generally unwell (signs of infection)
Pus or a painful swelling near the anus (possible abscess)
New or worsening inability to control stool or wind
Being unable to pass urine, with pain or a full feeling

Who to contact: your surgeon or clinic first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.

General guidance — it doesn't replace the specific advice your surgeon gives you.

Results & realistic expectations

A good result is a healed fissure and relief from the sharp pain, letting you open your bowels comfortably. Sphincterotomy heals the large majority of chronic fissures and is less likely to let them return than a botulinum toxin injection.

The operation does not remove the underlying tendency to constipation or hard stools. Keeping stools soft and not straining is what protects the result, so this becomes a long-term habit rather than a one-off treatment.

How long it lasts

Once a chronic fissure heals after a sphincterotomy, it usually stays healed. Fissures are more likely to return if constipation and straining continue. Looking after your bowel habit with fibre, fluids and not straining is the main thing that keeps the result lasting.

Combining with other procedures

A sphincterotomy is sometimes combined with a fissurectomy (trimming the chronic edges of the fissure) in the same operation. An examination under anaesthetic may be done at the same time to confirm the diagnosis if there is any doubt about the cause.

Follow-up & long-term care

You are usually reviewed after a few weeks to confirm the fissure is healing and that bowel control is normal. If the fissure has not healed or returns, your surgeon will discuss further options, which may include a different procedure such as an advancement flap.

Keep stools soft long term with enough fibre and fluid to avoid straining.
Treat constipation early if it comes back.
Report any return of pain, bleeding or problems with control promptly.

Revision and secondary surgery reality

If the fissure does not heal, options include a repeat procedure or switching to an advancement flap.
If continence problems persist, assessment and pelvic floor support may be needed.
A persistent or atypical fissure may need further investigation for another underlying cause.

Ask your surgeon for their own revision rate, what counts as a revision, and what is included in the written aftercare policy.

What good aftercare looks like

A written plan for keeping stools soft with fibre, fluids and laxatives.
A named contact route for problems such as bleeding, severe pain or signs of infection.
Review after a few weeks to confirm healing and check bowel control.
A clear plan for what happens if the fissure does not heal or continence is affected.

What affects the cost

Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:

Surgeon's fee and the anaesthetist's fee for the anaesthetic used
Theatre or facility fee for a day-case operation
Whether a fissurectomy or examination under anaesthetic is done at the same time
Follow-up appointments to check healing and bowel control
Any further treatment if the fissure does not heal or comes back
Medicines such as stool softeners, laxatives or creams afterwards

Make sure your written quote includes

The surgeon's fee and the anaesthetist's fee
The theatre or facility fee
What is included, and what happens if a different procedure is needed once inside
Follow-up appointments to check healing and continence
What happens, and what it costs, if the fissure does not heal or returns
The cancellation policy and what is covered if a complication occurs

On the NHS? A lateral sphincterotomy for a chronic fissure that has not healed with creams is commonly available on the NHS; private care may be used for faster access or choice of surgeon.

You're entitled to your total cost in writing — including aftercare and any revision — before you decide.

Choosing a surgeon safely

Check your surgeon is on the GMC Specialist Register for this area.
Make sure they practise at a CQC-registered location, and look for membership of bodies like BAAPS or BAPRAS.
You're entitled to a two-stage consent process with time to reflect (a cooling-off period). The surgeon who will operate must consent you — not a salesperson.
Be wary of pressure: time-limited offers, discounts or deposits taken before you've had time to think are red flags, not bargains.
You're entitled to your total cost in writing — including aftercare and any revision — before you decide.

How Vuemedics verifies every consultant →

Questions to ask your medical professional

Take this to your consultation. A good surgeon will welcome every one of these.

Why are you recommending a sphincterotomy rather than a Botox injection or advancement flap for me?
What is my personal risk of lasting trouble controlling wind or stool?
Have my creams, fibre and fluids been given a proper trial first?
How much of the muscle will you divide, and how do you limit the risk to control?
What is the chance the fissure heals, and the chance it comes back?
What will you do if it does not heal or returns?
Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
Will you be the surgeon who carries out my operation, and who looks after me afterwards?
What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
What does a realistic result look like — and what can this operation not achieve?
What are my options, including waiting, doing nothing for now, or choosing a different approach?
Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
What is the total cost in writing, including any follow-ups, and how much time do I have to decide?

Frequently asked questions

Will a sphincterotomy affect my bowel control?

It can. Minor, temporary trouble controlling wind is common in the early weeks. Lasting incontinence of solid stool is uncommon but possible, which is why the operation is chosen carefully and avoided in people who already have weak control.

Is a sphincterotomy better than a Botox injection?

It heals more fissures and they are less likely to return, but it permanently cuts part of the muscle. A botulinum toxin injection avoids cutting and carries less risk to control, but works less reliably. Which is right depends on your situation and how much continence risk matters to you.

How long does the operation take?

The operation itself is short, usually around 10 to 20 minutes, and is most often done as a day case.

How soon will the pain improve?

Many people notice the sharp fissure pain easing within days as the spasm is released, with the fissure healing over a few weeks.

Will the fissure come back?

It is less likely to return than after a botulinum toxin injection, but recurrence is possible, especially if constipation and straining continue. Keeping stools soft is the best protection.

Who should not have this operation?

It is generally avoided or used very cautiously in people who already have problems controlling stool or wind, including some women with past childbirth injury, because the risk to continence is higher. A different treatment may be safer.

Can I have it on the NHS?

Yes, it is commonly available on the NHS for a chronic fissure that has not healed with creams. Some people choose to be seen privately for speed or choice of surgeon.

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How we made this page

Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →

Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.

Sources & standards: StatPearls (NCBI) — Internal Anal Sphincterotomy NHS — Anal fissure Closed vs open lateral internal sphincterotomy: systematic review and meta-analysis (Scientific Reports) ACPGBI / Pescatori — Management of primary chronic anal fissure (position paper, PMC) Guy's and St Thomas' NHS FT — Anal fissure treatment: surgery Long-term incontinence after lateral internal sphincterotomy (PMC)

Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.

Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.